Executive
Summary

EPA has completed its review
of public comments on the revised risk assessments and is issuing its
risk management decision for ethion. The registrants of ethion requested
voluntary cancellation of their registrations for technical products with
risk mitigation measures to be effective in the interim. The EPA has accepted
this proposal. Two ethion tolerances will be revoked at this time, because
there are no currently registered uses for the associated crops. The remaining
15 tolerances will be revoked after the cancellation of ethion registrations
becomes effective.

The revised risk assessments
are based on review of the required target database supporting the use
patterns of currently registered products and new information received
during the reregistration process. The Agency invited stakeholders to
provide proposals, ideas or suggestions on appropriate mitigation measures
before the Agency issued its risk mitigation decision on ethion. After
considering the revised risks, as well as comments and mitigation suggestions
from stakeholders, EPA developed its risk management decision for uses
of ethion that pose risks of concern. This decision is discussed fully
in this document.

Ethion is an organophosphate
insecticide and acaricide used on citrus and cattle, first registered
in the late 1950's. Domestic use estimates range from approximately 860,000
lbs ai (Florida citrus only) in 1999 to a weighted average for the years
1987-1999 of approximately 1 million lbs ai total.

Overall Risk Summary

EPA's human health risk assessment
for ethion indicates some risk concerns. Food risk, both acute and chronic,
is not of concern. Drinking water risk estimates based on screening models
and monitoring data, exceed levels typically of concern in some cases,
but the Agency believes actual concentrations of ethion in drinking water
are much lower. Confirmatory data on the effect of water treatment would
have been required had the registrants not requested the voluntary cancellation
of their ethion registrations. There are concerns for workers who mix,
load, and apply ethion to citrus. Risks to applicators of ethion cattle
eartags could not be quantified, but the Agency believes it is prudent
to reduce exposures. Risks to some terrestrial and aquatic species are
of concern.

To mitigate risks of concern
posed by the uses of ethion during the phase-out period, EPA considered
mitigation proposals submitted by the stakeholders and decided on a number
of label amendments to address the occupational concerns. Results of the
risk assessments, and label amendments necessary to mitigate the risks,
are presented in this RED.

Dietary Risk

Acute and chronic dietary risk
assessments for food and drinking water are not of sufficient concern
to warrant mitigation for dietary exposures to ethion. The Agency expects
that risk estimates for drinking water, while exceeding levels of concern
in some cases, are high-end estimates and would likely have been reduced
based on data from water treatment studies. As indicated above, these
studies will not be required because ethion registrations are being phased-out.Occupational
Risk

Occupational exposures to ethion
are of concern to the Agency, and it has been determined that a number
of mitigation measures are necessary. For the use of ethion on citrus,
mixer/loader and applicator risk scenarios are of concern; i.e., Margins
of Exposure are less than 100 for both dermal and inhalation exposures.
During the phase-out period, these risks will be mitigated with the following
label restrictions for the use of ethion on citrus: restricted use classification;
only airblast applications will be allowed, with the exception of spot
treatments for snow scale; use of closed systems for mixing and loading
and enclosed cabs for applicators in airblast applications; spot treatment
for snow scale in limited volumes and with additional personal protective
equipment. Risks associated with reentry into areas treated with ethion
will be mitigated by increasing the restricted entry interval (REI) for
high exposure activities (i.e., harvest) to five days from two days for
all activities (an exception to the REI for low exposure activities will
remain at two days). For the use of ethion-impregnated cattle eartags,
risks will be mitigated with label language requiring the use of gloves
during application, in addition to baseline personal protective equipment.

Ecological Risk

The ecological risk assessment
indicates that some risks are of concern. The Agency has concluded that
measures already in place to reduce non-target exposures to ethion, in
combination with the restricted use classification, are adequate to address
these risk concerns during the phase-out period.

The Agency is issuing this Reregistration
Eligibility Document (RED) for ethion, as announced in a Notice of Availability
published in the Federal Register. This RED document includes guidance
and time frames for complying with label changes for products containing
ethion.

I. Introduction

The Federal Insecticide, Fungicide,
and Rodenticide Act (FIFRA) was amended in 1988 to accelerate the reregistration
of products with active ingredients registered prior to November 1, 1984.
The amended Act calls for the development and submission of data to support
the reregistration of an active ingredient, as well as a review of all
submitted data by the U.S. Environmental Protection Agency (referred to
as EPA or "the Agency"). Reregistration involves a thorough
review of the scientific database underlying a pesticide's registration.
The purpose of the Agency's review is to reassess the potential hazards
arising from the currently registered uses of the pesticide, to identify
the need for additional data on health and environmental effects, and
to determine whether the pesticide meets the "no unreasonable adverse
effects" criteria of FIFRA.

On August 3, 1996, the Food
Quality Protection Act of 1996 (FQPA) was signed into law. This Act amends
FIFRA to require tolerance reassessment during reregistration. It also
requires that by 2006, EPA must review all tolerances in effect on the
day before the date of the enactment of the FQPA, which was August 3,
1996. FQPA also amends the FFDCA to require a safety finding in tolerance
reassessment based on factors including an assessment of cumulative effects
of chemicals with a common mechanism of toxicity. Ethion belongs to a
group of pesticides called organophosphates, which share a common mechanism
of toxicity - they all affect the nervous system by inhibiting cholinesterase.
Although FQPA significantly affects the Agency's reregistration process,
it does not amend any of the existing reregistration deadlines. Therefore,
the Agency is continuing its reregistration program while it resolves
the remaining issues associated with the implementation of FQPA.

The implementation of FQPA has
required the Agency to revisit some of its existing policies relating
to the determination and regulation of dietary risk, and has also raised
a number of new issues for which policies need to be created. These issues
were refined and developed through collaboration between the Agency and
the Tolerance Reassessment Advisory Committee (TRAC), composed of representatives
from industry, environmental groups, and other interested parties. The
TRAC identified the following science policy issues it believed were key
to the implementation of FQPA and tolerance reassessment:

Applying the FQPA 10-Fold Safety Factor

Whether and How to Use "Monte Carlo" Analyses
in Dietary Exposure Assessments

How to Interpret "No Detectable Residues"
in Dietary Exposure Assessments

Refining Dietary (Food) Exposure Estimates

Refining Dietary (Drinking Water) Exposure Estimates

Assessing Residential Exposure

Aggregating Exposure from all Non-Occupational Sources

How to Conduct a Cumulative Risk Assessment for Organophosphate
or Other Pesticides with a Common Mechanism of Toxicity

Selection of Appropriate Toxicity Endpoints for Risk
Assessments of Organophosphates

Whether and How to Use Data Derived from Human Studies

The process developed by the
TRAC calls for EPA to provide one or more documents for public comment
on each of the policy issues described above. Each of these issues is
evolving and in a different stage of refinement. Some issue papers have
already been published for comment in the Federal Register and others
will be published shortly.

In addition to the policy issues
that resulted from the TRAC process, the Agency issued, on Sept. 29, 2000,
a Pesticide Registration Notice (PR 2000-9) that presents EPA's approach
for managing risks from organophosphate pesticides to occupational users.
The Worker PR Notice describes the Agency's baseline approach to managing
risks to handlers and workers who may be exposed to organophosphate pesticides.
Generally, basic protective measures such as closed mixing/loading systems,
enclosed cab equipment, or protective clothing, as well as increased reentry
intervals, will be required for most uses where current risk assessments
indicate a risk and such protective measures are feasible. The policy
also states that the Agency will assess each pesticide individually, and
based upon the risk assessment, determine the need for specific measures
tailored to the potential risks of the chemical. The measures included
in this RED are consistent with the Worker Pesticide Registration Notice.

This document consists of six
sections. This Section (Section I) contains the regulatory framework for
reregistration/tolerance reassessment and descriptions of the process
developed by TRAC for public comment on science policy issues for the
organophosphate pesticides and the worker risk management PR notice. Section
II profiles the use and usage of the chemical. Section III provides an
overview of the revised human health and environmental effects risk assessments
resulting from public comments and other information. Section IV presents
the Agency's reregistration eligibility and risk management decisions.
Section V summarizes label changes based on the risk mitigation measures
outlined in Section IV. Section VI provides information on how to access
related documents. The revised risk assessments and related addenda are
not included in this document, but are available on the Agency's web page
http://www.epa.gov/pesticides/op, and in the Public Docket.

II. Chemical
Overview

A. Regulatory History

Ethion was first registered
in the United States in the 1950's. In 1998, in response to risk concerns,
risk mitigation was implemented through reductions in the maximum application
rate and number of applications on citrus, prohibition of aerial applications,
restrictions on direction of airblast applications, and cancellation of
non-commercial uses of ethion.

The following information is
based on the currently registered uses of ethion.

Type of Pesticide: Non-systemic
insecticide/acaricide

Use Sites: Terrestrial food
and feed crops: Citrus fruits in Florida and Texas, including grapefruit,
lemon, lime, orange, tangelo, temples and tangerines. There is also a
single product registered as an eartag for use on beef and lactating dairy
cattle. No "public health" uses.

Rate: (Citrus) maximum of 2.5
lbs ai/A per application, with a maximum of two applications per year
(maximum 5.0 lbs ai/A/yr)

Spray Interval: 90 days

Use Classification: The 81.9%
EC formulation is restricted use; all other ethion end-use products are
general use products.

D. Estimated Usage of Ethion

This section summarizes the
best estimates available for the pesticide uses of ethion. These estimates
are derived from a variety of published and proprietary sources available
to the Agency, as well as information supplied by the registrants. Data
reflect annual fluctuations in use patterns as well as the variability
in data from various information sources. Between 800,000 and 1 million
lbs ai of ethion are used on citrus annually. No data were available for
the use of ethion in cattle eartags, although usage is likely to be quite
small.

Table 1: Estimated Usage of Ethion
on Citrus (sources: EPA, USDA, and National Center for Food and Agricultural
Policy)

Site

Acres Grown (000)

Acres Treated (000)

% of Crop Treated

LB AI Applied (000)

Average Application Rate3

Wtd Avg1

Est Max2

Wtd Avg

Est Max

Wtd Avg

Est Max

lb ai/ acre/yr

#appl/ yr

lb ai/ A/appl

Grapefruit

194

76

111

39.0%

57.0%

250

404

3.3

1.3

2.5

Lemons

63

0

0

0

0

0

1

NA

1.0

NA

Oranges

867

208

300

24.0%

34.6%

640

923

3.1

1.3

2.3

Temples

7

3

6

41.6%

83.1%

11

22

3.8

1.3

2.8

Limes

6

6

6

94.0%

100.0%

18

31

3.1

3.0

1.0

Tangelos

12

5

9

39.6%

59.5%

18

27

3.8

1.4

2.6

Tangerines

26

6

12

23.0%

46.0%

19

38

3.2

1.2

2.7

Total

-

-

-

-

-

956

1446

-

-

-

1 Wtd Avg = Weighted average
is based on data for 1987-1996; the most recent years and more reliable
data weighted more heavily; values are rounded to the nearest 1000 acres
treated
2 Est Max = Estimated maximum
3 Average application rates are calculated from weighted averages.

By contrast, the registrant
reports much lower usage in Florida (which should account for 97-98% of
use on citrus) in recent years:

Furthermore, EPA sources show
much greater usage in 1998 and 1999 (961,000 and 860,000 lbs ai), closer
to data from EPA sources.

Ethion usage can vary greatly
from year to year based on weather conditions, pest pressures, and overall
crop values. The year 1999 was a very dry year; the drought reduced yields,
and treatments with ethion and other crop inputs became less economical.
A registrant has indicated that the introduction of avermectin decreased
usage of ethion beginning about five years ago, but reported resistance
problems with avermectin appear to have boosted ethion usage for the last
several years (although that effect was offset by the dry weather conditions
in 1999).

III. Summary
of Ethion Risk Assessment

Following is a summary of EPA's
revised human health and ecological risk findings and conclusions for
the organophosphate pesticide ethion, as presented in the documents, "Human
Health Risk Assessment-Ethion," dated July 14, 1999, "Transmittal
of EFED List A: Summary Report for Ethion," dated September 9, 1994,
and subsequent addenda to the health risk document. The purpose of this
summary is to assist the reader by identifying the key features and findings
of these risk assessments, and in better understanding the conclusions
reached in the assessments.

The risk assessments for ethion
were presented at a July 14, 1999 briefing with stakeholders in Florida,
which was followed by an opportunity for public comment on risk management
for this pesticide. The risk assessments presented here form the basis
of the Agency's risk management decision for ethion.

A. Human Health
Risk Assessment

EPA issued its preliminary risk
assessment for ethion in August 1998 (Phase 3 of the TRAC process). In
response to comments and studies submitted during Phase 3, the risk assessments
were updated and refined. Major revisions to the human health risk assessment
are discussed below.

A major revision to the dietary
risk assessment involves the use of animal data to derive toxicological
endpoints. Past assessments had used data from studies with human test
subjects to derive endpoints. For the revised assessment, the Agency has
selected doses and endpoints to calculate dietary and non-dietary risk
based solely on animal studies. The use of animal data to derive endpoints
for ethion has resulted in an acute endpoint value which is ten-fold lower
than that which would have resulted from the use of the human data (0.0005
mg/kg/day versus 0.005 mg/kg/day for dietary routes). The revised assessment,
used an interspecies extrapolation factor informed by the similarities
between endpoint values from the human and animal studies-3X rather than
the usual 10X. The assessment on which the risk management decisions in
this document is based relies on the endpoint values from the animal study,
and an interspecies extrapolation factor of 10X. No further assessment
of ethion will be conducted in light of the voluntary cancellation.

Another revision to the preliminary
risk assessment is the recategorization of subpopulations for estimating
dietary risk. Due to low sample numbers, the subpopulations for nursing
and non-nursing infants have been combined and replaced with an "all
infants" categorization with greater statistical relevance.

The human health risk assessment
was revised to include drinking water and aggregate risk assessments.
These assessments, required by FQPA, were not part of the preliminary
assessment.

The revised risk assessment
is based largely upon current label requirements which include a number
of risk mitigation measures that had been implemented since the original
assessment was completed. These measures include a reduced application
rate from 3.0 lb ai/acre to 2.5 lb ai/acre, a reduced number of total
applications per year from 3 to 2, elimination of aerial applications,
restriction to spraying ethion in a direction away from bodies of water,
and the cancellation of all residential uses.

To clarify a change in terminology
which does not represent a substantive revision, the July 14, 1999 Human
Health Risk Assessment describes dietary risk in terms of the RfD, or
reference dose. An RfD adjusted with the appropriate FQPA safety factor
is termed a PAD, or population-adjusted dose. This is the terminology
which appears in this RED. In the case of ethion, the Agency determined
that no additional FQPA safety factor was needed to account for uncertainties
in the database or the special sensitivity of children. Had the interspecies
extrapolation factor not changed in this revision (as described above),
the acute PAD would be numerically identical to the acute RfD. As it is,
the difference between the acute RfD cited in the previous assessment
and the acute PAD cited in this document is a result of the change in
the interspecies extrapolation factor only, not the FQPA safety factor.

1. Dietary Risk from Food

a. Toxicity

The Agency has reviewed all
the submitted toxicity studies and determined that the toxicity database
is complete and supports a reregistration eligibility determination for
all currently registered uses of ethion. A brief overview of the endpoints
is outlined in Table 2 below. Further details can be found in the July
14, 1999 human health risk assessment and subsequent addenda.

* The NOAEL is based on plasma
cholinesterase inhibition at 0.5 mg/kg/day (LOAEL) observed in a chronic
toxicity study in dogs. The plasma cholinesterase inhibition observed
during Week 3 of the chronic study was utilized as the endpoint for the
acute dietary risk assessment because it occurred at the earliest point
in time for which data were available.

b. FQPA
Safety Factor

The FQPA Safety Factor was reduced
to 1X. The toxicity database includes an acceptable two-generation reproduction
study in rats and acceptable prenatal developmental toxicity studies in
rats and rabbits. These studies show no increased sensitivity to fetuses
as compared to maternal animals following acute in utero exposure in the
developmental rat and rabbit studies and no increased sensitivity to pups
as compared to adults in a multi-generation reproduction study in rats.
There was no evidence of abnormalities in the development of the fetal
nervous system in the pre/post natal studies. Sufficient actual data,
surrogate data, and/or modeling outputs are available to satisfactorily
assess dietary exposure and to provide a screening level drinking water
exposure assessment. The assumptions and models used in the assessments
do not underestimate the potential risk for infants and children. Therefore,
the 10X factor as required by FQPA was reduced to 1X.

c. Population
Adjusted Dose

The PAD is a term that characterizes
the dietary risk of a chemical, and reflects the Reference Dose, either
acute or chronic, that has been adjusted to account for the FQPA safety
factor (i.e., RfD/FQPA safety factor). In the case of ethion, the FQPA
safety factor is 1; therefore, the acute or chronic RfD is equal to the
acute or chronic PAD. A risk estimate that is less than 100% of the acute
or chronic PAD does not exceed the Agency's risk concern.

d. Exposure
Assumptions

For the dietary (food) risk
assessment, dietary exposure was estimated using PDP data for oranges,
which were translated to all citrus (grapefruit, tangelos, tangerines,
lemons, limes and kumquats); PDP data for orange juice, which were translated
to all citrus juices; negligible residues for milk (i.e., no ethion was
present); acute anticipated residues for meat; and food consumption data
from a 1977-1979 USDA food consumption survey. Percent crop treated data
were incorporated into the assessment. Exposure to the only metabolite
of toxicological concern (ethion monoxon) was not accounted for in the
assessment; the Agency has limited toxicity data on the metabolite and
it occurs in treated commodities at much lower levels than the parent
material.

A registrant conducted a chronic
dietary risk analysis for ethion using the Dietary Exposure Evaluation
Model (DEEM). DEEM incorporates consumption data generated in USDA's
Continuing Surveys of Food Intakes by Individuals (CSFII), 1989-91. The
chronic dietary exposure estimates resulting from this analysis are in
good agreement with EPA's assessment.

e. Food
Risk Characterization

Generally, a dietary risk estimate
that is less than 100% of the acute or chronic Population Adjusted Dose
(PAD) does not exceed the Agency's risk concerns. As can be seen in Table
3 below, the ethion acute dietary risk from food is below the Agency's
level of concern; that is, less than 100% of the acute PAD is utilized.
For example, for the most highly exposed subgroup, children (1-6 years),
the % acute PAD value is 43% at the 99.9th percentile of exposure.

Table 3. Acute Dietary Exposure
and Risk Estimates

Population

95th Percentile

99th Percentile

99.9th Percentile

Exposure mg/kg/d

% of Acute PAD

Exposure mg/kg/d

% of Acute PAD

Exposure mg/kg/d

US Population

0.000034

6.8

0.000066

13

0.000133

27

All Infants

0.000026

5.2

0.000075

15

0.000147

29

Children (1-6 years old)

0.000069

14

0.000120

24

0.000213

43

Children (7-12 years old)

0.000050

10

0.000087

17

0.000155

32

Females (13-50 years old)

0.000027

5.4

0.000045

9.0

0.000083

17

As can be seen in Table 4 below,
the chronic dietary risk from food alone is well below the Agency's level
of concern. For the most highly exposed subgroup, children (1-6 years),
the % chronic PAD value is 16%.

Table 4. Chronic Dietary Risk
Estimates for Ethion

Subgroup

Exposure (mg/kg/day)

% of Chronic PAD

U.S. population

0.000044

9

Children (1-6 years)

0.000081

16

These analyses could be refined
with data on ethion monoxon (the only metabolite of toxicological concern)
and monitoring data for commodities other than oranges.

2. Dietary
Risk from Drinking Water

Drinking water exposure to pesticides
can occur through groundwater and surface water contamination. EPA considers
both acute (one day) and chronic (lifetime) drinking water risks and uses
either modeling or actual monitoring data, if available, to estimate those
risks. Modeling typically provides a high-end estimate of risk.

The PRZM-EXAMS model was used
to estimate surface water concentrations, and SCI-GROW was used to estimate
groundwater concentrations. These are considered to be screening models.
There are also some monitoring data available for both surface and groundwater.

Groundwater monitoring data
and modeling results suggest that the potential for contamination from
ethion in groundwater is extremely low. Monitoring data come from the
Agency's Pesticides in Ground Water Database (9/92) and the Office of
Water's STORET system. Monitoring data indicate no detections in wells
even in Florida, where the greatest use occurs.

In contrast, ethion's fate characteristics
and monitoring indicate that surface water contamination is possible and
does occur. The drinking water assessment for ethion, therefore, is based
on surface water sources.

The only environmental degradate
of human toxicological concern is ethion monoxon. The environmental fate
characteristics of the monoxon are unknown at this time. Currently, there
is some uncertainty concerning whether or not this degradate would be
found in drinking water.

a. Drinking
Water Levels of Comparison (DWLOCs)

To determine the maximum allowable
contribution of drinking water pesticide residues in the diet, EPA first
looks at how much of the overall allowable risk is contributed by food
(and if appropriate, residential uses), and then determines a "drinking
water level of comparison" (DWLOC) to determine whether modeled or
monitoring levels exceed this level. The DWLOC is the maximum concentration
in drinking water which, when considered together with dietary exposure,
does not exceed a level of concern for dietary risk.

Details of the Agency's drinking
water analysis, which used screening models, are found in the HED Human
Health Risk Assessment (July 14, 1999) and the addendum dated May 17,
2000.

For acute risk, the potential
drinking water exposure for all populations derived from either ground
or surface water is of some concern. The DWLOC for the most highly exposed
subpopulation, all infants (<1 year old), is 3.4 ppb. The maximum modeled
concentration of ethion in surface water is 25 ppb. Even though the DWLOC
is exceeded, the Agency has determined that this acute drinking water
risk estimate is not of sufficient concern to warrant risk mitigation.
The reasons for this determination are explained below.

Monitoring of surface water
concentrations in an ethion high usage area and time found concentrations
of around 1.0 ppb (the circumstances are described further in the discussion
of drinking water chronic risk which follows). This value is much lower
than the value derived from surface water monitoring. Because the study
from which this value was obtained was not designed to account for daily
fluctuations in water concentrations of ethion, the 1.0 ppb value cannot
be used in determining acute risk. Nevertheless, it indicates that the
25 ppb value is a high-end estimate.

In addition, although the maximum
modeled surface water concentration exceeds the DWLOCs, ethion has a relatively
high soil/water partitioning coefficient which suggests that it will be
removed to some extent in the large majority of drinking water treatment
facilities through primary settling and flocculation/coagulation. Based
on the observed (monitored) concentration used for the chronic assessment,
which is considered a high-end assessment, the Agency believes that drinking
water from the tap would likely have concentrations of ethion which are
actually considerably less than the estimates used for this assessment.
A confirmatory study would have been required had the registrants not
requested the voluntary cancellation of their products.

For chronic risk, potential exposure
to drinking water derived from either surface water or groundwater is
not of concern for all populations. The DWLOC for the most highly exposed
subpopulation, children (1-6 years old), is 4 ppb; the DWLOC for the U.S.
population is 16 ppb. Model estimates of the average concentration of
ethion in surface water (6.6 ppb) exceed the former. However, based on
a review of surface water monitoring data, the Agency has concluded that
the surface water concentration which should be used for estimating chronic
exposure is 1.0 ppb. This value is a high-end concentration taken from
samples collected at peak ethion usage times, in the county with the greatest
citrus production in Florida, in a watershed where grapefruit production
is concentrated. Although this value informs our interpretation of the
acute drinking water risk assessment (as described above), it is not appropriate
to use it in estimating acute drinking water risk because the study from
which it was derived does not adequately address daily fluctuations in
ethion concentrations. Based on conclusions from the Florida monitoring
study, the chronic drinking water risk from ethion is not of concern.

3. Occupational
Risk

Workers can be exposed to a
pesticide through mixing, loading, and/or applying a pesticide, or re-entering
treated sites. Occupational handlers of ethion include: individual farmers
or growers who mix, load, and/or apply pesticides, professional or custom
agricultural applicators, and workers who enter treated areas to harvest
or perform maintenance tasks. Risk for all of these potentially exposed
populations is measured by a Margin of Exposure (MOE) which determines
how close the occupational exposure comes to a No Observed Adverse Effect
Level (NOAEL). Generally, MOEs greater than 100 do not exceed the Agency's
risk concern.

a. Toxicity

The toxicity of ethion is a
key component in assessing occupational risk. The risk calculations cited
in this document are based on the most current toxicity information available
for ethion, including a 21-day dermal toxicity study in rabbits. The toxicological
endpoints used in the occupational risk assessment for ethion are:

Short and intermediate-term dermal endpoint: brain
cholinesterase inhibition observed at the LOAEL of 1.0 mg/kg/day in
a 21-day dermal toxicity study in rabbits (MRID 00155499). The NOAEL
in this study is 0.8 mg/kg/day. A dermal absorption factor was not required.

Short and intermediate term inhalation: plasma cholinesterase
inhibition observed at the LOAEL of 0.5 mg/kg/day in the chronic dog
feeding study (MRID No. 41188401) . The NOAEL in this study is 0.05
mg/kg/day. An absorption factor of 100 percent was assumed for route
to route extrapolation (dietary to inhalation) in the absence of empirical
data.

In addition, the Agency cites
the following acute toxicity information:

Chemical-specific exposure data
were not available for ethion, so risks to pesticide handlers were assessed
using data from the Pesticide Handlers Exposure Database (PHED). Standard
assumptions such as average body weight, work day, and daily areas treated
were used to calculate risk estimates. Some PHED data are of better quality
than others, but all are the best data currently available to the Agency.
The quality of the data used for each scenario is discussed in the Human
Health Assessment document for ethion, which is available in the public
docket.

Anticipated use patterns, application
methods, and application rate were derived from current ethion product
labeling and discussions with ethion stakeholders. The maximum application
rate for airblast applications specified on labels of ethion products
used on citrus is 2.5 lbs. active ingredient per acre; the rate for the
spot treatment of snow scale is 0.05 lb. active ingredient per gallon.
The Agency typically uses acres treated per day values that are thought
to represent 8 solid hours of application work for most types of application
equipment.

Occupational handler exposure
assessments are conducted by the Agency for different levels of personal
protection. The Agency typically evaluates all exposures with minimal
protection and then adds additional protective measures using a tiered
approach to obtain an appropriate MOE (i.e., going from minimal to maximum
levels of protection). If the associated MOEs are less than 100 at one
tier, the Agency will assess increasing levels of risk mitigation (personal
protective equipment and engineering controls) until adequate MOEs are
obtained.

The current labels for ethion
require handlers to wear coveralls over short-sleeved shirt and short
pants, chemical-resistant gloves, chemical-resistant footwear with socks;
protective eyewear and chemical-resistant apron when mixing/loading, dust/mist
filtering respirator (outdoor exposure), and respirator with approved
pesticide cannister (indoor exposure). This level of protection did not
result in adequate MOEs; the additional levels of protection which were
used as the basis for estimates of exposure from ethion on citrus are:

Engineering controls: enclosed cab tractor and closed
mixing/loading system (with a single layer of clothing, and gloves for
mixer/loaders and airblast applicators). Engineering controls typically
are not applicable to handheld application methods.

The risk estimates for handlers
of ethion used on citrus are for short-term and intermediate-term exposures.
The Agency does not have reliable data for estimating exposure from the
cattle eartag use of ethion, for either exposure related to current labeling
or additional protective measures. The Agency evaluated measures which
it believes are prudent to reduce exposure from the eartag use.

Exposure to workers through
entry into citrus groves treated with ethion were also considered.

c. Occupational Handler
Risk Summary

Risks were assessed for mixer/loaders
supporting airblast and high pressure handwand applications of ethion
on citrus, applicators using airblast and high pressure handwand equipment
for ethion on citrus, and mixer/loader/applicators using backpack sprayers
and low pressure handwand equipment for ethion on citrus. These scenarios
are:

In addition, the Agency was
asked to consider a spot treatment application for snow scale on the trunk
and limbs of citrus trees which is part of an IPM program to control the
pest. The spot treatment of affected trees has a lesser impact on predators
of the snow scale than a whole-grove airblast treatment. The spot treatment
uses a high-pressure hand gun attached to a truck- or trailer-mounted
tank; the application rate is no more than 5 gallons per tree at 0.01
lb ai/gal with no more than 250 gallons applied by an applicator per day.

1) Occupational
Handler Risk

All these scenarios, evaluated
based on current label requirements, pose risks of concern. These risks,
based on combined dermal and inhalation exposures, are summarized in Table
6. The effects of additional controls on risk are also summarized. Risks
of concern, with MOEs less than 100, are associated with hand-held equipment
(high and low pressure handwands and backpack sprayers) even when wearing
added personal protective equipment, and for applicators operating airblast
sprayers from enclosed cab tractors. The added protective measures in
these cases represent the feasible maximum personal protective equipment
and engineering controls.

The MOE for mixer/loader/applicators
in the snow scale spot treatment in the low volume scenario described
above, wearing cotton coveralls over long-sleeved shirt and long pants,
shoes, socks, chemical- resistant gloves, a dust/mist respirator, chemical-resistant
apron for mixing and loading, and chemical-resistant headgear for overhead
exposures, is 73.

2) Post-Application Occupational
Risk

A post-application occupational
risk assessment for ethion was conducted for exposures in citrus orchards.
The assessment utilizes dislodgeable foliar residue (DFR) data for ethion
on citrus. Although the Agency considers these data to be the best available
DFR data, the subject study was deemed unacceptable by the Agency. It
was conducted at a higher application rate than the 2.5 lb. ai/A maximum.
Exposure estimates have been adjusted accordingly. The MOEs in Table 7
reflect that adjustment. The risk estimates in Table 7 also utilize new
transfer coefficient data.

Table 7. Summary of Margins of
Exposure for Restricted-Entry Intervals for Citrus

Time after Treatment

MOE Calculations

Ethion Only

Total: Ethion + Oxon*

12 hours

11

10

1 day

16

14

2 days

22

18

3 days

31

26

4 days

44

35

5 days

63

49

6 days

88

67

7 days

109

80

8 days

162

117

9 days

224

159

*Oxon represents
the total, monoxon plus dioxon.

The current REI for foliar treatments
with ethion is two days. As indicated in Table 7, the MOEs for reentry
do not rise above 100 until the ninth day following application. MOEs
less than 100 represent risks of concern.

4. Aggregate
Risk Characterization

An aggregate risk assessment
typically looks at the combined risk from dietary exposure (food and drinking
water routes) and residential exposure. Since ethion has no uses in which
residential exposure or other non-occupational exposure is likely, the
aggregate risk assessment for ethion is comprised of food and drinking
water dietary risks only. The aggregate exposure risk assessments appropriate
for ethion are acute (1-day) and chronic (lifetime) exposure.

The acute aggregate risk estimates
for ethion are not of sufficient concern to warrant risk mitigation. The
acute dietary risk for food only for the most highly exposed subpopulation
is estimated at 43% of the acute PAD. Groundwater monitoring data and
modeling results suggest that the potential for groundwater contamination
from ethion is extremely low. Modeling estimated environmental concentrations
(EECs) of ethion in groundwater of 0.05 ppb. This estimate is well below
the drinking water level of comparisons (DWLOCs) for the US population
of 13 ppb and the most highly exposed subpopulation (all infants) of 3.4
ppb.

Surface water modeling yields
a maximum EEC for ethion in surface water of 25 ppb. This estimate exceeds
the DWLOC for the US population of 16 ppb and the most highly exposed
subpopulation (all infants) of 3.4 ppb, but is considered a high-end estimate.
The relatively high soil/water partitioning coefficient of ethion suggests
that concentrations will be reduced in most surface water source drinking
water through typical methods employed in water treatment facilities.
Concentrations of ethion in drinking water which reaches the consumer
tap are likely to be considerably less than the estimates derived from
surface water modeling. The Agency would have required data on the effect
of typical water treatment methodologies on concentrations of ethion in
order to confirm this conclusion, but will not since ethion will be phased-out
in the near future.

The chronic aggregate risk estimates
are not of concern. The chronic dietary risk for food only for the most
highly exposed subpopulation is estimated at 16% of the PAD. The chronic
DWLOC for the US population is 16 ppb and for the most highly exposed
subpopulation (children 1-6) is 4 ppb. The groundwater EEC is 0.05 ppb,
and the Agency has reviewed extensive surface water monitoring data to
conclude that the surface water concentration which should be used for
estimating chronic exposure is 1.0 ppb. This estimate is less than the
chronic DWLOC for the most highly exposed subgroup, therefore, the Agency
has concluded that chronic aggregate risk from ethion is not of concern.

B. Environmental
Risk Assessment

A summary of the Agency's environmental
risk assessment is presented below. For detailed discussions of all aspects
of the environmental risk assessment, see the Environmental Fate and Effects
Division chapter, dated July 14, 1999, available in the public docket.

1. Environmental
Fate and Transport

Ethion is moderately persistent
in the environment. The primary routes of dissipation appear to be chemical
hydrolysis under alkaline conditions and microbial degradation. Ethion
degrades to carbon dioxide, ethion monoxon, ethion dioxon, and several
polar degradates including diethyl thiophosphate (ESOP), diethyl dithiophosphoric
acid (ESSP), and formaldehyde and/or thioformaldehyde. Under anaerobic
soil conditions, O,O-diethyl-S-(methylthio)methyl-phosphorodithioate was
also identified. The polar degradates and CO2 were the predominant products
in laboratory tests. After aging in soil for 30 days, ethion residues
were not mobile. The mobility of unaged ethion is not conclusively known
at this time. Based on the laboratory and field data submitted thus far,
including monitoring data compiled in EPA's Pesticides In Ground Water
Database, it is not expected that ethion will pose a threat to groundwater,
though it may accumulate in soil if multiple applications are made during
a growing season. The mobility of its toxicologically significant degradate,
ethion monoxon, is unknown. Volatilization from soil is not an important
route of dissipation.

Although it is not likely that
ethion will contaminate surface water by way of dissolved runoff, movement
into surface water may occur through erosion and/or spray drift. Microbial
degradation of ethion in soil is slow. In two studies in Florida orange
groves with sandy soils, ethion dissipated with half-lives of 67 to 68
days from the upper 6 inches at the drip line of trees, and 74 to 83 days
from the upper six inches from the rows between the trees treated with
ethion. The degradate ethion monoxide was also detected.

2. Risk to
Birds and Mammals

Ethion ranges from highly toxic
to practically nontoxic to birds on an acute oral basis. Ethion is practically
nontoxic to tested avian species on a subacute dietary basis. Avian reproductive
effects in the mallard duck may occur when residues levels are greater
than 75 ppm. Ethion is highly toxic to small mammals and bees on an acute
basis. Ethion residues are expected to occur on a large number of potential
food sources including seeds, fruits, and insects. Because numerous species
inhabit areas where ethion is used and birds often nest in trees or near
the areas where ethion is applied, exposure through dietary ingestion
or direct dermal application is a distinct likelihood.

Acute risk quotients for terrestrial
species at the maximum allowable application rate range from 0.012 to
0.41 and do not exceed high acute risk levels of concern, although restricted
use and endangered species levels of concern are exceeded. Chronic risk
quotients range from 0.8 to 27.6, in some cases exceeding chronic levels
of concern.

3. Risk to
Aquatic Species

Ethion displays very high toxicity
to most aquatic organisms tested. Even at the less than maximum application
rate of 1.0 lbs. ai/A, acute risk quotients exceed levels of concern for
aquatic invertebrates (with risk quotients ranging from 108 to 655) and
some fish species (risk quotients ranging from 0.12 to 0.74). Chronic
risk quotients exceed levels of concern for fish (risk quotients ranging
from 321 to 1921). There are no chronic data for invertebrates.

IV. Reregistration
Eligibility and Risk Management Decisions

A. Determination of Reregistration
Eligibility

Section 4(g)(2)(A) of FIFRA
calls for the Agency to determine, after submission of relevant data concerning
an active ingredient, whether products containing the active ingredient
are eligible for reregistration. The Agency identified and required the
submission of the generic (i.e., active ingredient-specific) data needed
to support the reregistration of products containing ethion.

The Agency has completed its
assessment of the occupational and ecological risks associated with the
use of pesticides containing the active ingredient ethion, as well as
an ethion-specific dietary risk assessment that has not considered the
cumulative effects of organophosphates as a class. The Appendix to this
document identifies the generic data requirements that the Agency reviewed
and lists the submitted studies that the Agency found acceptable.

As a result of its assessment
of the risks associated with ethion alone, EPA has determined that registrations
of ethion, unless amended as set forth in this document, present risks
inconsistent with FIFRA. The registrants have proposed the voluntary cancellation
of ethion registrations as well as phase-out dates, with risk mitigation
measures to be effective in the interim before cancellation. The sale
and distribution of ethion products will cease on December 31, 2003 by
the registrants, and these products may not be legally used after December
31, 2004.

B. Summary
of Phase 5 Comments and Responses

When making its reregistration
decision, the Agency took into account all comments received during Phase
5 of the OP Pilot Process. These comments in their entirety are available
in the docket. A brief summary of the comments and the Agency response
is noted here.

Comment: The Agency has improperly
removed the tenfold FQPA safety factor for ethion. In the absence of developmental
neurotoxicity testing, children cannot be shown to have no special sensitivity
to ethion. Risks associated with the contamination of residences adjacent
to treated areas and limited monitoring data have not been factored into
the safety factor decision-making.

Response: Because ethion is being
phased-out, exposures to children and to the general population will drop
off markedly in the next several years. The best data available to the
Agency show no differential pre- and post-natal effects for developmental
exposure to ethion, although the Agency would have required data specifically
on developmental neurotoxicity for use in refining risk estimates if ethion
were not being phased-out. Residential use of ethion has been prohibited
since 1998.

Comment: Exposures to ethion
cannot be considered to pose a reasonable certainty of no harm until the
cumulative assessment of the organophosphates is considered.

Response: The Agency has completed
its regulatory decision for ethion. Because all ethion registrations are
being canceled, the Agency believes that no additional risk mitigation
or risk assessment is necessary.

Comment: EPA has no basis for
using the results of human testing in the ethion risk assessment.

Response: The ethion risk assessment
was revised without using human data. Because of the voluntary cancellation,
no further revisions will be made.

Comment: Ethion has been used
for many years with few cases of worker exposure.

Response: The Agency has evidence
of a number of worker incidents associated with ethion exposure, which
it considers to lend support to the calculated risks. In general, the
Agency believes that such incidents are under reported and cannot be used
to quantify risk.

Comment: The greater risk estimate
for applicators relative to mixer/loaders is counterintuitive.

Response: The risk estimates
in Table 6 are estimates for increased levels of protection over the baseline.
Estimates for baseline PPE (that which is required by current labels)
show that dermal risks for mixer/loaders are greater than for applicators
while inhalation risks are greater for applicators. Risks are greater
overall for applicators with maximum PPE, suggesting that maximum PPE
is affording more protection to mixer/loaders than applicators.

Comment: Ethion is relatively
inexpensive to apply and affords good control of many pest species.

Response: The Agency agrees that
ethion can be a valuable tool in pest management, and has considered the
benefits of its use in making risk management decisions.

Comment: Because ethion is a
general use pesticide, it is available to small growers who would not
be able to purchase enclosed cabs with filters that remove pesticide residues
from the air.

Response: The Agency does not
believe an open cab tractor is adequately protective for any user, and
so has specified a general type of enclosed cab which does reduce potential
exposure. An extended timeline for implementing the enclosed cabs is intended
to help growers anticipate the need for these cabs and to more readily
acquire them. Additionally, between 50 and 70% of Florida citrus growers
are reported to already own enclosed cab tractors, and the Agency believes
that renting this equipment or paying for custom application with enclosed
cabs is relatively inexpensive.

Comment: An REI of nine or five
days would limit routine agricultural operations.

Response: The Agency considered
the economic impacts of the REI, as well as preliminary indications that
post-application exposures may actually be lower than the exposures on
which the quantitative assessment was based, to determine appropriate
REIs for citrus. In addition, the Agency has determined that a shorter
REI is appropriate for activities which would be expected to result in
less exposure than hand-harvesting of citrus fruits.

Comment: Restrictions on ethion
will increase costs for growers, reduce volume applied, and cause the
registrants to reconsider their support of the registrations.

Response: The Agency considered
available information on the benefits of ethion in making its risk management
decision. However, the considerable worker risk associated with this chemical
necessitated use of the maximum protection available, i.e., engineering
controls. The Agency is allowing time prior to the implementation of risk
mitigation to provide a transition period. In addition, the length of
the phase-out reflects the benefits of the chemical's use.

C. Regulatory
Position

1. FQPA Assessment

a. "Risk
Cup" Determination

As part of the FQPA tolerance
reassessment process, EPA assessed the risks associated with this organophosphate.
EPA has determined that risk from exposure to ethion is within its own
"risk cup." In other words, if ethion did not share a common
mechanism of toxicity with other chemicals, EPA would be able to conclude
today that the tolerances for ethion, with some adjustments, meet the
FQPA safety standards. In reaching this determination EPA has considered
the available information on the special sensitivity of infants and children,
as well as the chronic and acute food exposure. An aggregate assessment
was conducted for exposures through food and drinking water. Results of
this aggregate assessment indicate that the human health risks from these
combined exposures are considered to be within acceptable levels; that
is, combined risks from all exposures to ethion "fit" within
the individual risk cup.

b. Tolerance
Summary

In the individual assessment,
tolerances for residues of ethion (40 CFR §180.173) are presently
expressed in terms of ethion and its oxygen analog.

At the time when individual
organophosphates are being assessed for reregistration eligibility, the
Agency will commence proceedings to revoke and lower existing tolerances,
and correct commodity definitions. At this time, for ethion, the tolerances
listed in 40 CFR § 180.173 for ethion in dried tea and raisins will
be revoked. Ethion is not currently registered for use on tea or grapes
and the registrant does not intend to support these uses.

Tolerances on all other commodities
will be revoked in accordance with the phase-out schedule for ethion registrations.
The Agency is proposing at this time that these tolerances will be revoked
consistent with the anticipated final use date of December 31, 2004 and
a reasonable period for the passage of commodities with legal ethion residues
through the channels of trade.

The status of tolerances for
ethion is detailed in Table 8 below.

Table 8. Tolerance Summary for
Ethion

Commmodity

Current Tolerance (ppm)

Tolerance Reassessment (ppm)

Timing of Revocation Action

Tolerances listed under 40 CFR § 180.173

Cattle, fat

2.5

0.2

defer1

Cattle, meat (fat basis)

2.5

0.2

defer

Cattle, mbyp

1.0

0.2

defer

Citrus, fruits

2.0

5.0

defer

Citrus, pulp, dehydrated

10

25

defer

Dried tea

10

Revoke

following this RED

Goats, mbyp

0.2

0.2

defer

Hogs, fat

0.2

0.2

defer

Hogs, meat

0.2

0.2

defer

Hogs, mybp

0.2

0.2

defer

Horses, fat

0.2

0.2

defer

Horses, meat

0.2

0.2

defer

Horses, mbyp

0.2

0.2

defer

Milk fat

0.5

0.5

defer

Raisins

4

Revoke

following this RED

Sheep, meat

0.2

0..2

defer

Sheep, mybp

0.2

0.2

defer

Tolerances to be Proposed under 40 CFR §
180.173

Citrus, oil

N/A

55

defer

1 proposed revocation will be
consistent with last date of legal use

2. Endocrine
Disruptor Effects

EPA is required under the FFDCA,
as amended by FQPA, to develop a screening program to determine whether
certain substances (including all pesticide active and other ingredients)
"may have an effect in humans that is similar to an effect produced
by a naturally occurring estrogen, or other such endocrine effects as
the Administrator may designate." Following the recommendations of
its Endocrine Disruptor Screening and Testing Advisory Committee (EDSTAC),
EPA determined that there was a scientific basis for including, as part
of the program, the androgen and thyroid hormone systems, in addition
to the estrogen hormone system. EPA also adopted EDSTAC's recommendation
that the Program include evaluations of potential effects in wildlife.
For pesticide chemicals, EPA will use FIFRA and, to the extent that effects
in wildlife may help determine whether a substance may have an effect
in humans, FFDCA authority to require the wildlife evaluations. As the
science develops and resources allow, screening of additional hormone
systems may be added to the Endocrine Disruptor Screening Program (EDSP).

If ethion registrations are still
active when the appropriate screening and/or testing protocols being considered
under the Agency's EDSP have been developed, ethion may be subjected to
additional screening and/or testing to characterize effects related to
endocrine disruption.

3. Label Modifications and
Terms and Conditions of Registration

The registrants holding technical
registrations for ethion have agreed to amend labels to reduce risks to
workers and nontarget organisms in the interim prior to cancellation.

These amendments will result
in labeling changes effective for the 2002 use season; the labeling will
also inform users of the phase-out schedule. The legal sale and distribution
of ethion by the registrants will cease by December 31, 2003. The last
legal use date of ethion will be determined after publication of a notice
of voluntary cancellation as required by sec. 6(f) of FIFRA. Barring substantive
comment that date is likely to be December 31, 2004. The regulatory rationale
for each of the mitigation measures outlined below is discussed in the
section immediately following.

a. Citrus
Use

For use on citrus, the registrants
have agreed that:

All ethion products will be classified as Restricted
Use Pesticides, based on worker risk and risks to wildlife.

Only airblast applications will be allowed, except
for spot treatment of snow scale, and in both cases, only truck- or
trailer-mounted sprayers will be allowed. This restriction will eliminate
applications with high and low pressure handwands and backpack sprayers.

Product labels will be amended to specify that 1)
the spot treatments be made with a high-pressure hand-gun attached to
a truck- or trailer-mounted tank; 2) applicators making the spot treatments
wear cotton coveralls over long-sleeved shirt and long pants, shoes,
socks, chemical-resistant gloves, chemical-resistant headgear for overhead
exposures, and a dust/mist filtering respirator; 3) applicators use
no more than 2.5 lbs ai/day, diluting to 250 gallons for a final concentration
of 0.01 lb ai/gal.

Airblast applications will be made using enclosed
cabs. The type of enclosed cab required will be what is required by
the WPS and will be articulated on the product label as "as a cab
with a nonporous barrier that totally surrounds the occupants and prevents
contact with pesticides outside of the cab" and which provides
"protection equivalent to a dust/mist filtering respirator."
Alternatively, an enclosed cab affording dermal protection will be allowed
in conjunction with the use of a personal dust/mist filtering respirator.

Closed systems will be used for mixing/loading operations
which support airblast applications. The registrants have agreed that
production of product for use in 2002 and beyond will be in appropriate
containers.

For reentry into citrus groves which have been treated
with ethion the REI will be five days, with an exception for low exposure
activities (i.e., irrigation tasks and scouting) after two days.

The following is a summary of
the rationale for managing risks associated with the use of ethion. Where
labeling revisions are imposed, specific language is set forth in the
summary tables of Section V of this document.

1. Human Health
Risk Mitigation

a. Dietary
Risk Mitigation

Acute dietary risks are not
of sufficient concern to warrant risk mitigation in this area. Data would
have been required to assess the ability of water treatment plants to
remove ethion from surface water-sourced drinking water. These data will
not be required due to the phase-out. Chronic dietary risks are not of
concern, so no risk mitigation is required in this area.

b. Occupational
Risk Mitigation

Occupational risks associated
with ethion are significant. The registrants have agreed that all ethion
end-use products will be designated as Restricted Use Pesticides.

The risks associated with mixing,
loading, and applying ethion in low and high pressure handwand and backpack
sprayer equipment are of concern even when handlers wear the maximum practical
personal protective equipment. Engineering controls are not feasible for
the handwand and backpack sprayer equipment. The registrants have agreed
to remove the use of ethion in low pressure handwands, high pressure handwands,
and backpack sprayers from product labels. All products labeled for use
on citrus will bear language indicating that the product may only be applied
using an airblast sprayer and, for spot treatment of snow scale only,
a high-pressure hand-gun attached to a truck- or trailer-mounted tank.

The risks associated with mixing/loading
and application of ethion by airblast sprayers are of concern, although
these concerns are mitigated to some degree by the use of closed mixing/loading
systems and enclosed cab tractors. The registrants have agreed to amend
labels to indicate that product to be used in an airblast sprayer, beginning
in 2002, may only be mixed and loaded in a closed mixing/loading system.
The registrants have agreed that product to be used in 2002 and beyond
will be marketed in containers which are compatible with closed mixing/loading
systems as described in this document.

The registrants have also agreed
to amend labels to indicate that product applied with an airblast sprayer,
beginning in 2002, may only be applied from within an enclosed cab. This
enclosed cab is defined as a cab having a nonporous barrier that totally
surrounds the occupants and prevents contact with pesticides outside of
the cab and is equivalent in protection to a dust/mist filtering respirator.
Alternatively, applicators may use an enclosed cab which provides dermal
protection in conjunction with a personal dust/mist filtering respirator.

The risks associated with the
cattle eartag product have not been quantified, but the registrants have
agreed that it is prudent to require handlers to wear chemical-resistant
gloves and baseline personal protective equipment during handling.

Risk estimates for workers reentering
treated areas for up to eight days after treatment with ethion have MOEs
less than 100. The Agency has considered the potential economic impacts
associated with the inability of growers to fill packing house orders
if workers are not able to enter the fields to harvest fruit for longer
intervals after ethion is applied. Because citrus fruit of some varieties
becomes ready for harvest continuously over an extended period of time,
during which ethion is typically applied, a long REI would prevent some
harvest of fruit contracted for delivery to packing houses. The Agency
considered the potential impact of such failures to deliver to packing
houses at the designated times and the prospective cancellation of ethion
registrations in establishing an REI less than that required to raise
calculated MOEs over 100. The Agency also has identified low exposure
activities (irrigation activities and scouting) for which a shorter exception
to the reentry interval is thought to be appropriate. The registrants
have agreed to amend product labels to reflect an REI of five days, with
an exception for low exposure activities after two days.

c. Residential Risk Mitigation

There are no residential uses
for ethion, so no risk mitigation is required in this area.

2. Environmental
Risk Mitigation

Risk estimates for some wildlife
species are of concern for several citrus scenarios. The Agency has determined
that, while it is not possible to quantify the associated risk reduction,
risk mitigation implemented previously in the reregistration process (and
reflected on labels of ethion products for use on citrus) adequately addresses
risk concerns at this time, when viewed in conjunction with the new Restricted
Use classification. These measures include, for use on citrus, a reduction
of the maximum application rate to 2.5 lb ai/A, reduction of the number
of total applications per year to 2, elimination of aerial applications,
requirement for spraying ethion in a direction away from adjacent bodies
of water, and the cancellation of all residential uses.

E. Other Labeling
Requirements

The Agency has identified other
use and safety information to be placed on the labeling of all end-use
products containing ethion. For the specific labeling statements, refer
to Section V of this document

1. Endangered
Species Statement

The Agency has developed the
Endangered Species Protection Program to identify pesticides whose use
may cause adverse impacts on endangered and threatened species, and to
implement mitigation measures that will eliminate the adverse impacts.
At present, the program is being implemented on an interim basis as described
in a Federal Register notice (54 FR 27984-28008, July 3, 1989), and is
providing information to pesticide users to help them protect these species
on a voluntary basis. As currently planned, but subject to change as it
develops, the final program will call for any necessary label modifications
referring to required limitations on pesticide uses, typically as depicted
in county-specific bulletins or by other site-specific mechanisms as specified
by state partners. A final program will be described in a future Federal
Register notice. At this time, the Agency is not requiring label modifications
for ethion specific to the protection of endangered species. Any requirements
for product use modifications in the future will occur under the Endangered
Species Protection Program.

A 1989 opinion on ethion from
the US Fish and Wildlife Service found the potential for jeopardy to a
number of invertebrate, amphibian and fish species. The Service provided
"reasonable and prudent alternatives" to reduce exposure of
these jeopardized species to ethion. Effects to endangered birds and mammals
were not assessed in this opinion. The Agency subsequently concluded that
it is unlikely that endangered birds and mammals are exposed from the
use of ethion on citrus. Although some endangered species are found in
the Florida counties where citrus is grown, their habitat and food preferences
would likely preclude their use of citrus groves as habitat or feeding
areas.

The registrants of ethion have
agreed to the future cancellation of their registrations, and during the
phase-out period risks are be mitigated by new measures and measures which
have been in place for several years. These measures include the Restricted
Use classification, elimination of aerial application, reduction of the
application rate to 2.5 lb ai/A/application with no more than two applications
per year, directional spraying of citrus with airblast sprayers away from
surface water.

Although many additional species,
especially aquatic species, have been federally listed as endangered/threatened
since the biological opinion of 1989 was written, the Agency believes
that the continued use of ethion with the agreed-upon risk reduction measures,
particularly the elimination of aerial applications, the reduction in
application rate, and directional application--coupled with the phase-out
of ethion use anticipated by December 31, 2004--will not affect any additional
species not covered by the 1989 biological opinion.

2. Spray Drift
Management

The Agency has been working with
the Spray Drift Task Force, EPA Regional Offices and State Lead Agencies
for pesticide regulation and other parties to develop the best spray drift
management practices. The Agency is proposing interim mitigation measures
for aerial applications that should be placed on product labels/labeling
as specified in section V of this document . The Agency has completed
its evaluation of the new database submitted by the Spray Drift Task Force,
a membership of U.S. pesticide registrants, and is developing a policy
on how to appropriately apply the data and the AgDRIFT computer model
to its risk assessments for pesticides applied by air, orchard airblast
and ground hydraulic methods. After the policy is in place, the Agency
may impose further refinements in spray drift management practices to
reduce off-target drift and risks associated with aerial as well as other
application types where appropriate. Since ethion is no longer applied
aerially, labels will be amended to include the following spray drift
related language.

"Do not apply this product in a way that
will cantact workers or other persons, either directly or through drift.
Only protected handlers may be in treated area during application.

"Do not allow spray to drift from the application
site and contact people, structures people occupy at any time, non-target
property on which those structures are located, animals, non-target crops,
parks and recreation areas, aquatic and wetland areas, forests, pastures,
and rangelands.

"For airblast applications, apply only when
wind speed is 10 mph or less at the application site, as measured by an
anemometer outside of the orchard on the upwind side.

"The applicator must use all other measures
necessary to control drift in addition to the drift control measures listed
above."

V. What Registrants Need
to Do

In order to maintain registration during the phase-off
period, registrants need to implement the risk mitigation measures outlined
in Section IV. Additionally:

For each product containing ethion,
registrants need to submit the following items within two months of the
date of this document:

(1) an application for registration
amendment (EPA Form 8570-1, filled in, with a description on the application,
such as, "Responding to Reregistration Eligibility Decision"
document);

(2) five copies of the draft
label incorporating all label amendments outlined in Table 9 of this document;

Also, a Data Call-In Notice
(DCI) was recently sent to registrants of organophosphate pesticides currently
registered under FIFRA (August 6, 1999, 64 FR 42945-42947;
August 18, 1999, 64 FR 44922-44923). DCI requirements included acute,
subchronic, and developmental neurotoxicity studies; the due date is September
2001. Acute and chronic neurotoxicity studies have been submitted and
found acceptable. Because ethion registrations are being voluntarily canceled,
EPA is not requiring the data listed above at this time

2. Labeling for Manufacturing-Use
Products

Manufacturing use product (MUP)
labeling will be revised as agreed by the Agency and the registrants and
will comply with all current EPA regulations, PR Notices, and applicable
policies. The MUP labeling should bear the language contained in Table
9 at the end of this section.

B. End-Use Products

1. Additional Product-Specific
Data Requirements

Section 4(g)(2)(B) of FIFRA
calls for the Agency to obtain any needed product-specific data regarding
the pesticide after a determination of eligibility has been made. Because
ethion registrations will be canceled in the near future, EPA will not
require such data.

2. Labeling for End-Use Products

Labeling changes are necessary
to implement the mitigation measures outlined in Section IV above. Specific
language to implement these changes is detailed in Table 9 at the end
of this section.

C. Existing Stocks

Registrants and persons other
than the registrant remain obligated to meet pre-existing Agency imposed
label changes and existing stocks requirements applicable to products
they sell or distribute. As agreed by the Agency and the registrants,
the sale and distribution of ethion by the registrants will cease on December
31, 2003; barring any substantive comment, the last use date for ethion
products is anticipated to be December 31, 2004.

D. Labeling Changes Summary
Table

Table 9. Summary of Labeling Changes for Ethion

Description

Amended Labeling Language

Placement on Label

Manufacturing Use Products

Statement describing allowed uses.

"Only for formulation into
an insecticide/acaricide for the following uses: air blast treatment
on citrus, spot treatment for snow scale control on citrus, and as
a cattle eartag."

"This chemical is toxic to
wildlife. Do not discharge effluent containing this product into lakes,
streams, ponds, estuaries, oceans or other waters unless in accordance
with the requirements of a National Pollutant Discharge Elimination
System (NPDES) permit and the permitting authority has been notified
in writing prior to discharge. Do not discharge effluent containing
this product to sewer systems without previously notifying the local
sewage treatment plant authority. For guidance contact your state
Water Board or Regional Office of the EPA."

Directions for Use

General Sale and Distribution Restrictions

"The sale and distribution
of this product is prohibited after [October 1, 2003]. The use of
this product is prohibited after [December 31, 2003]."

Directions for Use

All End-Use Products

General Application Restrictions

"The sale and distribution
of this product by the registrants is prohibited after [December 31,
2003]. The sale and distribution of this product by anyone other than
the registrants is prohibited after [October 1, 2004]. The use of
this product is prohibited after [December 31, 2004]."

Place in the Directions for Use
directly above the Agricultural use Box

End-Use Products for Use on Citrus

Restricted Use Pesticide Requirement

"Restricted Use Pesticide"

This product is a Restricted Use Pesticide due to worker and
ecological risk.

"For retail sale to and use only by Certified Applicators
or persons under their direct supervision and only for those uses
covered by the Certified Applicators certification."

Top of first page of label

All End-Use Products

ProductsPPE Requirements
Established by the RED

"Personal Protective Equipment (PPE)"

Some materials that are chemical-resistant to this product are
(registrant inserts correct chemical-resistant material). If you
want more options, follow the instructions for category (registrant
inserts A,B,C,D,E,F,G,or H) on an EPA chemical-resistance category
selection chart."Mixers, loaders, applicators and other handlers
supporting airblast applications must wear:

Long-sleeved shirt & long pants

Shoes plus socks

Chemical-resistant gloves and chemical-resistant apron for
mixers and loaders and persons exposed to concentrate.

"Follow manufacturer's instructions for cleaning/maintaining
PPE. If no such instructions for washables exist, use detergent
and hot water. Keep and wash PPE separately from other laundry.

"Discard clothing or other absorbent materials that have
been drenched or heavily contaminated with this product's concentrate.
Do not reuse them."

Precautionary Statements: Hazards
to Humans and Domestic Animals (immediately following the PPE requirements)

Engineering Controls

"Engineering Controls"

Mixers and loaders must:
-- use a closed mixing/loading system with a dry disconnect system
designed by the manufacturer to enclose the liquid pesticide to
prevent it from contacting handlers or other people AND the system
must be functioning properly and must be used and maintained in
accordance with the manufacturer's written operating instructions.

"Mixers and loaders must also:

wear the personal protective equipment required for mixers/loaders
in the PPE section of this labeling,

wear protective eyewear if the system operates under pressure,
and

have immediately available for use in case of an accident

a dust/mist filtering respirator (MSHA/NIOSH approval number
prefix TC-21C), or

a NIOSH -approved respirator with any R, P or HE filter,
and

coveralls and chemical-resistant footwear."

"Applicators using airblast equipment must use an enclosed
cab, defined as a cab with a nonporous barrier that totally surrounds
the occupants and prevents contact with pesticides outside of the
cab. The enclosed cab must meet the requirements in the Worker Protection
Standard for Agricultural Pesticides [40 CFR 170.240(d)(5)] for
inhalation protection providing at least as much respiratory protection
as the type of dust/mist filtering respirator specified in the PPE
section of this labeling.

"Alternatively, applicators using airblast equipment may
use an enclosed cab that meets the definition in the Worker Protection
Standard for Agricultural Pesticides [40 CFR 170.240(d)(5)] for
dermal protection. In addition, applicators using this type of cab
must wear the type of dust/mist filtering respirator specified in
the PPE section of this labeling.

"All such applicators, regardless of which type of enclosed
cab they are using, must also:

wear the personal protective equipment required in the PPE
section of this labeling for applicators using airblast equipment

be provided and must have immediately available for use in
an emergency when they must exit the cab in the treated area:
coveralls, chemical-resistant gloves, chemical-resistant footwear,
chemical-resistant headgear, if overhead exposure, and a respirator
of the type specified in the PPE section of this labeling

e off any PPE that was worn in the treated area before reentering
the cab, and tak

store all such PPE in a chemical-resistant container, such
as a plastic bag, to prevent contamination of the inside of the
cab."

"Users should remove PPE immediately after handling this
product. Wash the outside of gloves before removing. As soon as
possible, wash thoroughly and change into clean clothing."

Precautionary Statements under:
Hazards to Humans and Domestic Animals immediately following Engineering
Controls(Must be placed in a box.)

Environmental Hazards

"Environmental Hazards

"This chemical is toxic to wildlife. Spray last three rows
windward of surface water, using nozzles on grove side only, with
spray directed away from surface water. Avoid spray going over tops
of trees by adjusting or turning off top nozzles. Shut off nozzles
on the side away from the grove when spraying the outside row. Shut
off nozzles when turning at ends of rows and passing gaps in rows.
Do not contaminate water when cleaning equipment or disposing of
equipment washwaters."

"Do not enter or allow worker
entry into treated areas during the restricted entry interval (REI)
of five days. Exception: In addition to early-entry exceptions allowed
by the WPS, you may enter and or allow workers/handlers to enter treated
areas to perform irrigation and/or scouting tasks 3 days after application,
as long as at least long pants, long-sleeved shirt, shoes, and socks
are worn. Notify workers of the exception (including when entry is
permitted for each of the tasks named in the exception) by warning
them orally OR by posting warning signs at the entrances to treated
areas."

Directions for Use, Agricultural
Use Requirements Box

Early Entry Personal Protective
Equipment

"PPE required for early entry
to treated areas that is permitted under the Worker Protection Standard
and that involves contact with anything that has been treated, such
as plants, soil, or water, is:-- Coveralls over short-sleeved shirt
and short pants-- Chemical-resistant gloves made of waterproof material--
Chemical-resistant footwear plus socks- Chemical-resistant headgear
for overhead exposures."

Directions for Use, Agricultural
Use Requirements Box

Double Notification Statement

"Notify workers of the application
by warning them orally and by posting warning signs at entrances to
treated areas."

General Application Restrictions

"Do not apply this product
in a way that will contact workers or other persons, either directly
or through drift. Only protected handlers may be in the area during
application."Do not allow spray to drift from the application
site and contact people, structures people occupy at any time, non-target
property on which those structures are located, animals, non-target
crops, parks and recreation areas, aquatic and wetland areas, forests,
pastures, and rangelands."For airblast applications, apply only
when wind speed is 10 mph or less at the application site, as measured
by an anemometer outside of the orchard on the upwind side."The
applicator must use all other measures necessary to control drift
in addition to the drift control measures listed above."

Place in the Directions for Use
directly above the Agricultural Use Box

Site Specific Application Restrictions

"This product may only be applied to citrus."Note to
registrant: All other sites must be removed from all product labels."This
product may only be applied to citrus via airblast sprayer or, for
spot treatment of snow scale on citrus, via high-pressure hand-gun
attached to a truck- or trailer- mounted tank. All other application
methods are prohibited."Note to registrants: The label must
reflect the application rate restrictions noted below:The maximum
use rate for citrus via airblast is 2.5 lbs. ai/A per application.
The maximum number of applications for citrus via airblast is two
per year.Applicators of spot treatments for snow scale must use
no more than 2.5 lbs ai/day, diluting to 250 gallons for a final
concentration of 0.01 lb ai/gal. Applications for snow scale must
not exceed more than 250 gal of material diluted in this way each
day. The application rate is 3-5 gallons per tree to the trunk and
limbs on trees where snow scale is present.

Direction for Use under General
Precautions and Restrictions and/or Application Instructions

Cattle Eartag Products

Site Specific Application Restrictions

"This product may only be used
as a cattle eartag."

Direction for Use under General
Precautions and Restrictions and/or Application Instructions

PPE required for products used as
"eartags" on cattle

"Applicators of cattle eartags
impregnated with ethion must wear:-- Long-sleeved shirt and long pants--
Socks and shoes-- Chemical-resistant gloves, such as (registrant inserts
correct glove types)"

Precautionary Statements under Hazards
to Humans and Domestic Animals

VI. Related Documents
and How to Access Them

This Reregistration Eligibility
Document is supported by documents that are presently maintained in the
OPP docket. The OPP docket is located in Room 119, Crystal Mall #2, 1921
Jefferson Davis Highway, Arlington, VA. It is open Monday through Friday,
excluding legal holidays, from 8:30 am to 4 pm..

The docket initially contained
preliminary risk assessments and related documents as of August 13, 1998.
Sixty days later the first public comment period closed. EPA then considered
comments, revised the risk assessment, and added the formal "Response
to Comments" document and the revised risk assessment to the docket
on July 14, 1999.

All documents may be viewed in the OPP docket
room, in hard copy form, or downloaded or viewed via the Internet at the
following site: http://www.epa.gov/pesticides/op.